Surfing the web, I found the following explanations on how to produce the diphthongs [aʊ] and [aɪ]:

"/aʊ/ as in all the words of "How now brown cow!". The starting position is the vowel sound /æ/ as in "at" "bad" or "rat" with tongue front but also low (i.e. mouth open). To make the diphthong the journey for your tongue from front low (mouth very open) to back high (small tight mouth aperture) is a very long excursion. Your jaw will move a lot too."

"/aɪ/ as in sky, buy, cry, tie. The starting position is /æ/, the same sound as in "cat". To make the diphthong you need a big jaw movement, moving the tongue from front open to and front close."

Are these the correct ways to produce these two diphthongs in American English?

The explanation that says that /aʊ/ starts in /æ/ makes sense to me because that's what I hear, but I'm not sure about the second one. I don't think /aɪ/ starts in /æ/.

Could you please tell me in which vowel these two diphthongs start?

  • 1
    Henry Higgins from My Fair Lady would probably say both start with the "ah" sound, as in the words car, are, burrow, and London when spoken with a British accent.
    – Lawrence
    Nov 22, 2015 at 16:45
  • If you start with [æ], you'll sound kind of weird. See A Course in Phonetics (Ladefoged & Johnson). In the sixth edition, there's a chart on pages 90 and an explanation on pages 92-93. Not sure about the new edition.
    – user28567
    Nov 22, 2015 at 17:22
  • 2
    I don't start with /æ/. I start somewhere between /æ/ and /ɑ/, and probably closer to /æ/. The right IPA symbol for this is probably /a/, but I suspect the people writing the explanations didn't want to introduce a new IPA symbol. I think /æɪ/ is how some Australians pronounce mate. Nov 22, 2015 at 17:49
  • I just found the section I was referring to on Google Books: books.google.com/books?id=FjLc1XtqJUUC&pg=PA90
    – user28567
    Nov 22, 2015 at 18:06
  • 2
    I think this might be better suited to Linguistics.SE. Even as toddlers, native speakers very quickly learn to ignore huge differences in exactly how any given sound is articulated, since it makes no difference so long as we can assign them reasonably accurately to the small number of phonemes that are semantically distinct in English. As we get older we do this even more (without consciously noticing), since in context we can often guess what a sound should be even if it was wrongly articulated. Nov 22, 2015 at 18:21

1 Answer 1


Per SoundComparisons, the /aʊ/ in "mouth" can be realized in a variety of ways in different American accents, but most seem to start at either [æ] or the more open [a]. The /aʊ/ in "cow" shows roughly the same range.

From the same source, the /aɪ/ in "five" typically starts with the more open and more central [ä]. The /aɪ/ in "white" can be realized the same way, but in some accents it starts higher at [ɐ]. This is because the American version of Canadian raising (see Wikipedia) affects /aɪ/ but not /aʊ/.

  • Plus we have the Northern Cities Shift moving all the vowels around now. Oct 6, 2023 at 18:21

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